Blackberry yellow vein disease is the most important viral disease of blackberry in the United States.Experiments were conducted to characterize a new virus identified in symptomatic plants. Molecularanalysis revealed a genome organization resembling Grapevine leafroll-associated virus 3, the type speciesof the genus Ampelovirus in the family Closteroviridae. The genome of the virus, provisionally namedblackberry vein banding associated virus (BVBaV), consists of 18,643 nucleotides and contains 10 openreading frames (ORFs). These ORFs encode closterovirid signature replication-associated and quintuplegene block proteins, as well as four additional proteins of unknown function. Phylogenetic analysesof taxonomically relevant products consistently placed BVBaV in the same cluster with GLRaV-3 andother members of the subgroup I of the genus Ampelovirus. The virus population structure in the U.S.was studied using the replication associated polyprotein 1a, heat shock 70 homolog and minor coatproteins of 25 isolates. This study revealed significant intra-species variation without any clusteringamong isolates based on their geographic origin. Further analyses indicated that these proteins are understringent purifying selections. High genetic variability and incongruent clustering of isolates suggestedthe possible involvement of recombination in the evolution of BVBaV.